WASHINGTON — Sales of previously owned homes edged up slightly in December, the National Association of Realtors reported Thursday, helping to lift sales for the year to the highest level in seven years.

Sales increased to an annual rate of 4.87 million units last month, up 1 percent from the November sales pace. However, both months represented a slower pace of sales than earlier in 2013, reflecting the drag from higher mortgage rates and higher home prices.